In a galvanometric scanner system, variable resistors and other elements are used to adjust driver circuit constants of a scanner driver, which is an analog driver, according to a variety of drive modes (drive modes based on, for example, different loads, drive patterns, and response characteristics) so as to optimize the operating characteristics of the scanner driver.
For example, a galvanometric scanner system for light beam scanning includes a galvanometric scanner for oscillating a mirror for light beam scanning within a predetermined angular range and a dedicated scanner driver for driving the galvanometric scanner. A function generator or an external command generator that includes a personal computer and a D/A converter provides a real-time drive command to the scanner driver so as to drive the galvanometric scanner according to predetermined drive control specifications.
The scanner driver includes a plurality of variable resistors and other elements for adjusting the operating characteristics of the scanner driver. To adjust the operating characteristics, an adjuster is connected to the galvanometric scanner and the adjuster is used to adjust the variable resistors and other elements so as to optimize the driver circuit constants in such a way that operating characteristics most suitable to a drive mode are obtained.
For example, optimal operating characteristics of the scanner driver in a case where the galvanometric scanner is to be moved at high speed over a wide range (coarse control) differ from those in a case where the galvanometric scanner is to be moved with high positioning precision over a short distance (fine control). To drive the galvanometric scanner from a position A to a target position B, it is necessary to change an applied command voltage from the command voltage “a” corresponding to the position A to the command voltage “b” corresponding to the position B. The change from the command voltage “a” to the command voltage “b”, which are outputted from the external command generator, corresponds to a command for the scanner driver only indicative of the final target position B. Therefore, the path and time from the position A to the position B are set by adjusting the circuit constants of the analog scanner driver. For example, in a case where the drive pattern is set in such a way that the difference between the command voltages “a” and “b” is large, it is necessary to adjust the circuit constants of the scanner driver so as to optimize the operating characteristics in such a way that the galvanometric scanner can be driven with no large amount of overshoot.
Patent Document 1 discloses a galvanometric scanner system using analog input and output values. In Patent Document 1, a variety of drive patterns are stored and held in the scanner driver to drive the galvanometric scanner in an optimal manner. Patent Document 2 discloses a limited-rotation electromagnetic motor with a detector that can be used as a galvanometric scanner for mirror scanning.
[Patent Document 1] JP-A 2005-338450
[Patent Document 2] JP-A 7-31119
As described above, in a galvanometric scanner system, a plurality of variable resistors and other elements are manipulated to adjust the driver circuit constants so as to optimize the operating characteristics of the scanner driver for a variety of drive modes.
To optimize the operating characteristics of the scanner driver, however, it is necessary to adjust a large number of parameters. For example, to adjust the control gain, damping characteristics, integration constant, filter characteristics (resonance characteristics), and robustness of the scanner driver, it is necessary to manipulate a large number of variable resistors, variable capacitors, and other elements. Therefore, the adjusting is not readily performed and is time-consuming.
Since the use of such an adjustment method does not allow flexible adjustment of the scanner driver, optimal operation cannot be achieved when the drive mode of the galvanometric scanner is changed after the adjustment. In this case, it is necessary to connect an adjuster again to the scanner driver and change the variable resistance and other parameters so as to perform adjustment for optimizing the driver operating characteristics (circuit constants). Such adjustment is time-consuming and difficult to perform on the user side.